1. Field of the Invention
The present invention relates to a system for treating a substrate using a supercritical fluid and, more particularly, to a system for flowing a high temperature supercritical fluid.
2. Description of Related Art
During the fabrication of semiconductor devices for integrated circuits (ICs), a sequence of material processing steps, including both pattern etching and deposition processes, are performed, whereby material is removed from or added to a substrate surface, respectively. During, for instance, pattern etching, a pattern formed in a mask layer of radiation-sensitive material, such as photoresist, using for example photolithography, is transferred to an underlying thin material film using a combination of physical and chemical processes to facilitate the selective removal of the underlying material film relative to the mask layer.
Thereafter, the remaining radiation-sensitive material, or photoresist, and post-etch residue, such as hardened photoresist and other etch residues, are removed using one or more cleaning processes. Conventionally, these residues are removed by performing plasma ashing in an oxygen plasma, followed by wet cleaning through immersion of the substrate in a liquid bath of stripper chemicals.
Until recently, dry plasma ashing and wet cleaning were found to be sufficient for removing residue and contaminants accumulated during semiconductor processing. However, recent advancements for ICs include a reduction in the critical dimension for etched features below a feature dimension acceptable for wet cleaning, such as a feature dimension below approximately 45 to 65 nanometers (nm). Moreover, the advent of new materials, such as low dielectric constant (low-k) materials, limits the use of plasma ashing due to their susceptibility to damage during plasma exposure.
Therefore, at present, interest has developed for the replacement of dry plasma ashing and wet cleaning. One interest includes the development of dry cleaning systems utilizing a supercritical fluid as a carrier for a solvent, or other residue removing composition. At present, the inventors have recognized that conventional processes are deficient in, for example, cleaning residue from a substrate, particularly those substrates following complex etching processes, or having high aspect ratio features.